/*
 * crc8.c
 *
 *  Created on: 2023/10/16
 */

/*
 * The MIT License (MIT)
 *
 * Copyright (c) 2023 Takayoshi Uemitsu (BestTechnology CO.,LTD.)
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 *
 */

#include <stdint.h>

#include "crc8.h"

// Peripheral CRCs are used to store data flash, so we'll do the math straight up here.
// Polynomial 0x1d, Ini Value 0xff, Final xor Value 0xff

static const uint8_t CRC8_SAE_J1850[256] = {
    0x00, 0x1D, 0x3A, 0x27, 0x74, 0x69, 0x4E, 0x53, 0xE8, 0xF5, 0xD2, 0xCF, 0x9C, 0x81, 0xA6, 0xBB,
    0xCD, 0xD0, 0xF7, 0xEA, 0xB9, 0xA4, 0x83, 0x9E, 0x25, 0x38, 0x1F, 0x02, 0x51, 0x4C, 0x6B, 0x76,
    0x87, 0x9A, 0xBD, 0xA0, 0xF3, 0xEE, 0xC9, 0xD4, 0x6F, 0x72, 0x55, 0x48, 0x1B, 0x06, 0x21, 0x3C,
    0x4A, 0x57, 0x70, 0x6D, 0x3E, 0x23, 0x04, 0x19, 0xA2, 0xBF, 0x98, 0x85, 0xD6, 0xCB, 0xEC, 0xF1,
    0x13, 0x0E, 0x29, 0x34, 0x67, 0x7A, 0x5D, 0x40, 0xFB, 0xE6, 0xC1, 0xDC, 0x8F, 0x92, 0xB5, 0xA8,
    0xDE, 0xC3, 0xE4, 0xF9, 0xAA, 0xB7, 0x90, 0x8D, 0x36, 0x2B, 0x0C, 0x11, 0x42, 0x5F, 0x78, 0x65,
    0x94, 0x89, 0xAE, 0xB3, 0xE0, 0xFD, 0xDA, 0xC7, 0x7C, 0x61, 0x46, 0x5B, 0x08, 0x15, 0x32, 0x2F,
    0x59, 0x44, 0x63, 0x7E, 0x2D, 0x30, 0x17, 0x0A, 0xB1, 0xAC, 0x8B, 0x96, 0xC5, 0xD8, 0xFF, 0xE2,
    0x26, 0x3B, 0x1C, 0x01, 0x52, 0x4F, 0x68, 0x75, 0xCE, 0xD3, 0xF4, 0xE9, 0xBA, 0xA7, 0x80, 0x9D,
    0xEB, 0xF6, 0xD1, 0xCC, 0x9F, 0x82, 0xA5, 0xB8, 0x03, 0x1E, 0x39, 0x24, 0x77, 0x6A, 0x4D, 0x50,
    0xA1, 0xBC, 0x9B, 0x86, 0xD5, 0xC8, 0xEF, 0xF2, 0x49, 0x54, 0x73, 0x6E, 0x3D, 0x20, 0x07, 0x1A,
    0x6C, 0x71, 0x56, 0x4B, 0x18, 0x05, 0x22, 0x3F, 0x84, 0x99, 0xBE, 0xA3, 0xF0, 0xED, 0xCA, 0xD7,
    0x35, 0x28, 0x0F, 0x12, 0x41, 0x5C, 0x7B, 0x66, 0xDD, 0xC0, 0xE7, 0xFA, 0xA9, 0xB4, 0x93, 0x8E,
    0xF8, 0xE5, 0xC2, 0xDF, 0x8C, 0x91, 0xB6, 0xAB, 0x10, 0x0D, 0x2A, 0x37, 0x64, 0x79, 0x5E, 0x43,
    0xB2, 0xAF, 0x88, 0x95, 0xC6, 0xDB, 0xFC, 0xE1, 0x5A, 0x47, 0x60, 0x7D, 0x2E, 0x33, 0x14, 0x09,
    0x7F, 0x62, 0x45, 0x58, 0x0B, 0x16, 0x31, 0x2C, 0x97, 0x8A, 0xAD, 0xB0, 0xE3, 0xFE, 0xD9, 0xC4,
};

uint8_t CalcCRC8 (const void *buf, size_t size) {
    uint8_t *data = (uint8_t *)buf;
    uint8_t crc8 = 0xFF;

    while (size-- != 0) crc8 = CRC8_SAE_J1850[crc8 ^ *data++];
    return crc8 ^ 0xff;
}

uint8_t GetCRC8 (uint8_t *crc, uint8_t dat) {
  *crc = CRC8_SAE_J1850[(*crc) ^ dat];
  return *crc;
}
